EP1880046B1 - Spinning preparation machine and contactless measuring method - Google Patents

Description

The invention relates to a spinning preparation machine and a non-contact measuring method according to the preambles of the independent claims.

There are various non-contact measuring methods and corresponding devices for determining the distance of clothing tips known. For example, in the DE 42 35 610 A1 discloses an inductive sensor associated with the lid of a card and facing the roller assembly. In the DE 102 51 574 A1 an optical sensor is described which is able to detect the distance between the free ends of the trimmings and corresponding reference surfaces. The DE 39 13 996 A1 also discloses non-contact sensors, in which case capacitive, inductive and optical sensors are mentioned.

Indirect measuring methods are those in which the immediate distance of the opposing clothing tips is not measured. An example of this is in the above DE 42 35 610 A1 which discloses a distance measurement of the drum set to a flat bar in which only the sensors are accommodated. According to the DE 39 13 996 A1 are provided on the front sides of the fittings sensor, which are associated with the card drum and measure the distance to opposite counterparts on the lid. It is also known to determine the distance between the sliding shoes, which are attached via cover heads to the flat bars, to the flat fitting. From these indirect distance measurements is then closed on the immediate distance of the clothing tips.

DE100 53 139 A1 discloses a device on a spinning preparation machine, e.g. B. card, cleaner o. The like., For setting distances to trimmings, in which a garnished roller with a garnished counter surface, z. B. lid, cooperates and in which the distance between the garnished areas is changeable. In order to allow adjustment of the carding gap, a contact between the tips of the set of at least one flat bar and the tips of the drum set by displacement of the flat bars can be produced and released again and the contact can be detected by a device.

The aforementioned devices and methods have the disadvantage that on the one hand they are expensive and on the other hand often provide averaged distance values only over a larger number of clothing needles or clothing teeth. In addition, a calibration based on a hand measurement is necessary.

It is an object of the present invention to propose a cost-effective and precise measuring method and a corresponding spinning preparation machine for non-contact measurement and / or adjustment of the distance between two opposing trimmings and / or their wear and / or the measurement of their spatial position to each other.

This object is achieved in the spinning preparation machine or the method of the type mentioned by the features of the independent claims.

The advantages of the invention are in particular that a direct distance measurement between the tips of relatively moving sets can be performed. By the clothing tips themselves are used as sensors, also an extremely cost-effective solution is realized. The provoked electrical discharges in the form of voltage and / or current discharges make it possible, in particular, to deduce from the potential difference between the clothing tips prevailing during the voltage discharge, how great the distance between the said tips is. Here, the frequency and / or the number and / or the type of discharges can be observed and / or evaluated. By means of the method according to the invention, such direct distance measurements can also be realized in the smallest distance ranges, in particular between 0 and 0.5 mm. In addition, the invention allows individual distance measurements between each lid to the drum set and / or between certain zones of the flat set to the drum set, as will be explained later. In addition, the invention offers the advantage that measurements can be performed regardless of material properties, humidity and temperature, if these effects are averaged out.

Preferably, an evaluation unit is provided, which evaluates the inventive distance determination between clothing tips on the basis of the aforementioned parameters (frequency, number, type of discharges and evaluation of the electrical parameters in electrical discharge). Such a computer-aided evaluation provides fast and precise values for improved adjustment of the Clothing tips to each other, which increases the performance of the machine. Preferably, the evaluation unit evaluates the measured values and gives the operator - for example on a machine display - instructions on how he has to change the distance between the sets. Also, the operator can alternatively or additionally be issued information about the current state of wear of the trimmings and / or about the inclination angle (tightening angle) of the flat clothing over the drum, as will be explained later.

In a particularly advantageous embodiment, the voltage value is registered immediately before a voltage discharge from a voltage measuring device. This voltage value is in direct functional relationship to the smallest distance of the opposing clothing tips in the voltage discharge, so that a precise determination of this distance is possible.

A precise determination of the breakdown voltage or the voltage during voltage discharges is possible if the voltage source is designed as a pulse generator which is capable of generating a variable voltage, for example a sawtooth-shaped voltage or a DC voltage with sawtooth-shaped tips. In the latter case, the constant component, i. the DC voltage, expediently the smallest permissible distance between the clothing tips. The maximum tension preferably corresponds at least to the largest expected clothing spacing. The breakdown is expediently caused in each case during the voltage increase in order to pick up the currently prevailing voltage during the voltage discharge and to evaluate the spacing of the clothing tips.

The presence of fibers in the clothing gap can lead to premature high-voltage discharges due to the residual moisture present, which can falsify the measurement results. In order to avoid such influences, preferably after a voltage discharge by applying a suitable potential difference in the low-voltage region for a short time, a plasma discharge with a plasma current flow between the clothing tips be caused. This phenomenon can be exploited by determining the voltage needed to maintain the plasma current (also falling within the terminology of the invention under the term "electrical discharge"). This voltage is also called plasma extinction voltage. The smallest distance between the clothing tips is a function of this erase voltage and the plasma current and thus easily determined by computational evaluation. The above-mentioned potential difference in the low-voltage region is dependent on the clothing tip spacing and is not influenced by the residual moisture of the fibers.

Particularly preferably, the machine according to the invention has an additional pair of electrodes, between which voltage or spark discharges are provoked. This electrode pair serves as a reference measuring unit, wherein the distance of the two electrode tips is known. This distance can be changed defined according to a preferred embodiment, whereby here, too, the new distance of the electrode tips must be known. The additional electrode pair preferably has a similar surface geometry as the trimmings. Due to the known distance between the reference electrodes and the comparable surface geometry, influences of the surface geometry on the measured values of the voltage discharges between the sets can be reduced by means of the evaluation unit. This procedure thus increases the accuracy of the distance calculation between the clothing tips.

The additional reference electrode pair may alternatively or, preferably, be used in addition to calculate the influences of the micro-operating environment and / or the set geometries on the electrical discharge measurements between the sets. For this purpose, the reference electrodes are to be placed in the same micro-operating climate as the sets. The term "micro-operating climate" is to be understood in particular as the air temperature, the air humidity, the air velocity, the presence of ionizing particles and / or residual ionizations. In particular, the geometry of the clothing should be understood to mean the values of the point angles of the clothing and the values of the peak radii. The The aforementioned parameters have an influence on the corona effect and thus on the magnitude of the discharge voltage.

Advantageously, the additional electrode pair is arranged outside the carding area of the spinning preparation machine designed as a carding machine in order not to influence the carding process or to reduce its efficiency. It has also proved to be advantageous if the additional pair of electrodes is arranged in a space in which substantially no fibers can penetrate during operation of the spinning preparation machine, so that these no fiber-related breakdowns or other influence on the measurement results with the reference electrodes including a flight of the measuring space can cause. Further, when passing through the measuring space an air stream containing substantially no fibers and originating from the carding area, the micro-operating climate in the measuring space is substantially identical to that between the two sets.

With appropriate design of the machine, a user may additionally or alternatively perform optical control of the spark discharges provided they are bright enough to observe them more closely. For this purpose, for example, provide a visible gap through which the gap between the trimmings can be observed.

In a preferred embodiment, one set is designed as a flat set of a card and the other set as an associated drum set. Especially the distance between these two sets is relevant for the carding result, so that an optimal setting is of great advantage. Since virtually all the clothing tips involved in the carding process can be used as sensors, an extremely precise distance determination and thus distance adjustment is possible.

The same applies in the case of a card, in which the invention can be implemented similarly as in a card.

In particular, when determining the distance between two relatively moving sets (either in the same or inverse sense), the method according to the invention is advantageously applicable, since due to the movements of the components involved and the carding the risk of a rapid change in distance exists and thus by adjusting the sets to each other can be reacted quickly.

In most applications, the potential difference between the tips of the momentarily opposite arranged clothing tips is measured when occurring voltage discharge; Therefore, appropriate taps for these voltage values are necessary. It is advisable to provide in the case of the distance measurements between the cover and drum sets corresponding sliding contacts on the flat bars and / or the drum shaft, wherein at least one of the contacts is connected to the voltage source. The other contact may be grounded or also connected to the voltage source.

There are several ways to tap the electrical values. In one possibility, e.g. all covers measured, for example, at certain measuring points along the flat set fixed measuring points are provided with which each lid comes into electrical contact during its movement. For this purpose, each short sliding contacts or brushes are provided at the measuring points, which detect only a single cover. The advantage lies in the possibility of monitoring individual lids, for example, to determine any damage and / or the individual clothing wear.

In another possibility, the traveling lid is measured over a larger, possibly even over the entire, the drum opposite running area. In such a measurement over the entire carding area, it is preferable to use a long sliding contact or a long grinding brush, which extends over the entire raceway of the revolving cover. The advantage here lies in the possibility of checking and monitoring the position accuracy of the flexible sheet, the drum, the drum shield and / or the flat bars under load, ie during operation, and during the thermal conditions arising during production.

Of course, a combination of the two methods is also possible, e.g. on one side of the machine the short brushes and on the other the long brush are provided.

An electrical insulation between the two sets is advantageously designed such that the flat bars rest on the front side on two sliding arcs, said sliding arches are made of electrically non-conductive plastic or provided with such a plastic layer. Such bends are preferably flexible bows on which the lid heads of the flat bars are guided while passing on the drum set. This electrical insulation ensures the voltage discharge between the clothing tips.

A high accuracy of the distance detection can be obtained when the potential differences for the voltage discharge between the sets over the entire carding width are generated. The device according to the invention or the method according to the invention thus make possible a large-area sensor which covers a substantially larger measuring area than the known sensors. If a spark discharge is triggered on this surface, the operator receives an indication of the smallest available distance of all opposing clothing tips and can react accordingly.

The above-described sliding contact on the flat bar usually has electrical contact with all clothing tips due to the Garniturnadelanbringung the clothing strip. Therefore, in this case, the exact location of the spark discharge can not be located. In contrast, a spatially resolved measurement provides more precise statements. For this purpose, between the flat bar and clothing strips at least one at least partially electrically conductive surface element may be provided, which has electrical contact with the clothing tips facing away from the clothing ends. With spark discharges thus current flows from the clothing tips over the Contact the trimmings with the electrically conductive surface element to the voltage source to close the circuit. This at least one electrically conductive surface element can be localized, for example, at locations of the clothing strip which are known to be relevant on the flat rod.

According to an advantageous embodiment, the at least one surface element has a plurality of electrically isolated guide zones distributed on the surface element. It is advisable to distribute these guide zones over the length and / or across the width of the associated clothing strip in order to make special location statements about the voltage discharges and thus about the smallest distance between the associated clothing tips in the respective sections. About appropriate taps and signal lines, these control zones are each connected to the voltage source and the voltage measuring device, which is at voltage discharges, the evaluation unit due to the different circuits capable of distinguishing the control zones from each other.

In general, by evaluating the signal from various electrical taps, which are electrically insulated from one another and associated with a cover, which are assigned to different carding zones of the cover, the condition of the tips in the various carding zones can be assessed.

In a similar, likewise advantageous method, the state of the flexible sheet can be assessed on the basis of signals of such electrical taps, which are assigned to different carding zones of the cover, when these carding zones are arranged one behind the other in the direction of rotation.

Since the trimmings are moved relative to each other, advantageously a voltage having a repeat sequence of a plurality of successive rising and falling edges is used. Advantageously, in this case the repetition sequence is set to the maximum expected relative speed between the clothing tips and to the largest expected clothing peak density.

Preferably, a maximum distance-related potential difference produced between the clothing tips is adjustable, which exceeds the dielectric strength of the air (about 3 200 V / mm) and, depending on the desired measurement range, lies in the range between 1000 and 10 000 V. It has proven to be advantageous if this range is adjustable between 2,000 and 5,000 V, and preferably between 2,500 and 3,500 V. At a carding gap of about 0.4 mm, the calculated breakdown voltage is about 1 280 V.

The discharge energy at spark discharge should amount to less than 10 mJ, otherwise there would be a fire and electric shock hazard. Also, the clothing tips would be worn by electroerosion over masses. Preferably, the discharge energy is even less than 5 mJ and preferably less than 1 mJ. With these discharge energies, there is no danger to the operator if he accidentally short circuits the circuit with his body.

A further development of the method according to the invention is characterized in that statistical calculations are carried out by the evaluation unit in order to eliminate the effects of fibers in the clothing gap on the measurement results. As a result, the statistical evaluation provides measured values for spark discharge in fiber-free air, which contain an accurate statement about the actual clothing tip spacing. Of course, it is alternatively or additionally possible to perform measurements without the presence of fibers in order to make such or similar statements.

According to a further development of the invention, the clothing tip spacing determined by the method according to the invention can be used to automatically optimally adjust the distance. For this purpose, corresponding adjustment means are provided which set the clothing spacing on the basis of the arithmetic evaluation and / or the optical control on the part of the operator. Preferably, the evaluation unit after determining the clothing spacing control commands to the adjustment. These adjustment means are, for example, actuators, which act on the curve of the flexible bend around the sliding blocks of the flat bars raise or lower, so as to increase the clothing tip distance or to reduce.
According to a further development of the method according to the invention for adjusting the spacing of the clothing tips, it is proposed that a successive adjustment of the two flat-top end faces be carried out. For this purpose, the distance is initially reduced on the first side such that a desired distance value δ is set on the basis of the registered and / or observed spark discharges. Under certain circumstances, this can be controlled by means of the conventional techniques of the measuring rods to be introduced into the carding nip. This distance value δ corresponds to a breakdown voltage value U _E = f (δ) or a piasm current-dependent erasing voltage U _P = f (δ, I _P ). Subsequently, the second end face of the corresponding flat bar is approximated by means of the flexible arch. As long as the distance between the newly set cover side to the drum δ _N ≥ δ, due to the inclination of the lid sparks arise on the first side of the cover; Thus, the electrical measurement parameters U _E = f (δ) and U _P = f (δ, I _P ) initially remain unchanged. But as soon as the distance between the second cover side to the drum δ _N δ <, sparking changes the page and the new breakdown voltage value is U _EN = f (δ _N) <U _E and is dependent from the plasma stream new erase voltage U _PN = f (δ _N , I _P ) <U _P. Since in this case the second distance has fallen below an optimum value, the second end side is then raised again until the new breakdown voltage value U _EN = U _E or the new deletion voltage U _PN = U _P dependent on the plasma current. This ensures that the new distance value δ _{N also} assumes the setpoint value δ. Here, the lid is now parallel to the drum. This procedure ensures a substantially equal distance over the entire carding width of the flat bar.

In a particularly simple but effective application of the method according to the invention, the discharge voltage is used as a collision warning when falling below a predetermined distance of the clothing tips. If the tips are very close to each other, the discharge voltage is correspondingly low, so that in particular when falling below a predetermined discharge voltage, a collision indication by means of a corresponding signal apparatus, z. B. acoustically and / or visually, and / or a suitable measure is taken to prevent the Kolission.

Advantageous developments of the invention are characterized by the features of the subclaims.

Figur 1

eine schematische Seitenansicht einer Karde;

Figur 2

eine Seitenansicht eines Deckelstabs mit einem Teil einer Kardentrommel;

Figur 3

eine Vorderansicht eines Deckelstabs mit einem Teil einer Kardentrommel;

Figur 4

eine schematische Darstellung der Funkenerzeugung zwischen einer Deckelgarnitur und einer Trommelgarnitur;

Figur 5

ein Schaltbild einer Messanordnung zur Messung der Entladungsspannung;

Figur 6

ein Spannungs-Zeit-Diagramm sowie ein Strom-Zeit-Diagramm zur Darstellung der Funkenentladungen;

Figur 7

ein Schaltbild einer Messanordnung für die Messung eines Plasmastroms;

Figur 8

ein Spannungs-Zeit-Diagramm zur Darstellung eines Plasmastroms, ersichtlich im darunter befindlichen Strom-Zeit-Diagramm;

Figur 9

ein Faserleitelement in Seitenansicht mit integriertem Referenzelektrodenpaar, geschnitten entlang der Linie I-I in der Figur 10;

Figur 10

die Anordnung der Figur 9 in Aufsicht;

Figur 11

eine zweite Ausführungsform eines Referenzelektrodenpaares in Seitenansicht;

Figur 12

eine dritte Ausführungsform eines Referenzelektrodenpaares in Seitenansicht;

Figur 13

eine perspektivische Sicht auf einen Deckelstab mit elektrisch leitendem Flächenelement zwischen Deckelstab und Garniturstreifen;

Figur 14

eine vergrösserte Seitenansicht eines Garniturstreifens mit eingesteckten Garniturnadeln sowie Flächenelement;

Figur 15

eine erste Ausführungsform elektrisch leitender Flächenelemente in Unteransicht;

Figur 16

eine zweite Ausführungsform elektrisch leitender Flächenelementen in Unteransicht;

Figur 17

eine schematische Seitenansicht einer Wanderdeckelanordnung mit drei unabhängigen Messstellen;

Figur 18

eine Darstellung der gemessen Kardierspaltwerte an den drei Messstellen in Abhängigkeit der Zeit;

Figur 19

eine schematische Seitenansicht einer Wanderdeckelanordnung mit drei langgestreckten Schleifkontakten entlang des Kardierwegs eines Deckelstabs, und

Figur 20

eine Darstellung von hypothetisch gemessenen Kardierspaltwerten an den drei Schleifkontakten in Abhängigkeit vom Messbereich β.

In the following the invention will be explained in more detail with reference to FIGS. Show it:

FIG. 1

a schematic side view of a card;

FIG. 2

a side view of a flat rod with a part of a card drum;

FIG. 3

a front view of a flat bar with a part of a card drum;

FIG. 4

a schematic representation of the spark generation between a flat fitting and a drum set;

FIG. 5

a circuit diagram of a measuring arrangement for measuring the discharge voltage;

FIG. 6

a voltage-time diagram and a current-time diagram illustrating the spark discharges;

FIG. 7

a circuit diagram of a measuring arrangement for the measurement of a plasma stream;

FIG. 8

a voltage-time diagram for representing a plasma stream, seen in the underlying current-time diagram;

FIG. 9

a fiber guide in side view with integrated reference electrode pair, cut along the line II in the FIG. 10 ;

FIG. 10

the arrangement of FIG. 9 in supervision;

FIG. 11

a second embodiment of a reference electrode pair in side view;

FIG. 12

a third embodiment of a reference electrode pair in side view;

FIG. 13

a perspective view of a flat bar with electrically conductive surface element between the flat bar and clothing strips;

FIG. 14

an enlarged side view of a clothing strip with inserted Garniturnadeln and surface element;

FIG. 15

a first embodiment of electrically conductive surface elements in a bottom view;

FIG. 16

a second embodiment of electrically conductive surface elements in a bottom view;

FIG. 17

a schematic side view of a traveling lid assembly with three independent measuring points;

FIG. 18

a representation of the measured carding gap values at the three measuring points as a function of time;

FIG. 19

a schematic side view of a traveling lid assembly with three elongated sliding contacts along the carding path of a flat bar, and

FIG. 20

a representation of hypothetically measured carding gap values at the three sliding contacts in dependence on the measuring range β.

In the FIG. 1 a known carding machine 1 is shown, wherein flakes F are fed from a hopper 2 to a feed roller 3 and a subsequent brush cutter 4. The carding machine 1 comprises a single drum 5 (master cylinder or so-called drum), which is rotatably supported in a frame. The drum 5 works in a known manner with a traveling lid assembly 6, a fiber feeding system 7, which in particular includes the feed roller 3 and the breeze 4, and a fiber pickup 8 together, the latter in particular has a so-called. Carding elements 10 can be arranged in the front, rear and lower carding zones of the carding machine 1. Between the revolving lid arrangement 6 and the carding elements 10, fiber guiding elements not shown in detail are arranged, which will be discussed in more detail later. The fiber-receiving system 8 conveys the sliver FB to a schematically indicated sliver storage 11.

At the aforementioned moving lid assembly 6, a plurality of flat bars 13 is provided, wherein in the FIG. 1 only individual bars 13 are shown schematically. Currently used traveling lid assemblies 6 include closely spaced a plurality of flat bars 13 that rotate. For this purpose, the flat bars 13 in the vicinity of their respective end faces of endless belts 18 (see FIG. 3 ) and moved against the direction of rotation of the drum 5 and passed on the underside of the traveling lid assembly 6 to the drum 5.

FIG. 2 shows a flat bar 13 viewed from the front side. A central portion 14 of the flat bar 13 is formed as a hollow profile. In this case, a central web 15 is provided to increase the stability of the flat bar 13. On the underside of the central portion 14 is a clothing strip 20 with a flat clothing 21, consisting from a multiplicity of clothing needles, fastened by means of clips or clamps 16. The flat bar 13 is guided in the direction of movement D on a provided with a drum set 25 outer surface of a drum 5, which rotates in the direction T. The drum assembly 25 has a plurality of schematically illustrated clothing tips which are circumferentially distributed over the drum surface.

In a carding nip δ between the flat clothing 21 and the drum set 25, the carded fiber flakes are dissolved up to the individual fiber, which also experience a significant longitudinal orientation. In addition, any remaining impurities, including dust, are eliminated, part of the existing short fibers eliminated and nits dissolved. In order for these tasks to be carried out properly, it is essential that the width of the carding gap δ, which is only a few tenths of a millimeter, be correctly maintained.

FIG. 3 shows the flat bar the FIG. 2 in a broken longitudinal view. He has at its two end faces in each case a lid head 17, which is inserted into the lower hollow portion of the flat bar 13. Each lid head 17 is provided on its underside with a sliding shoe 19 which rests on the two respective end face of the flat bar 13 arranged flexible sheet 12 to form a sliding surface G and slides along these flexible sheets 12. In the lid heads 17 also engage the upper side, the two endless belts 18 a. For clarity, the brackets 16 in the FIG. 3 not shown.

Due to the curvature of the drum surface and the adapted course of the flexible sheets 12, the clothing needles of the flat clothing 21 over the width B of the flat bar 13 at different distances to the drum set 25. In the FIG. 2 these are the distances denoted by δ, δ ₁ and δ ₂ , where the distance denoted by δ is the smallest. These different distances can - depending on where and how signals from discharges are tapped over the surface of the clothing strip 20 - be taken into account in the evaluation. Particularly in the determination of the tightening angle designated by Θ, which indicates the angle of inclination of the flat clothing 21 relative to the drum 5 and a function of the distances δ ₁ , δ ₂ and the radius of the drum (r _drum ) and the said width B, the voltage discharges are required and evaluated at the respective outer thread needles. A correspondingly trained signal tap will be explained later. In the FIG. 4 schematically shows the spark generation and the measurement of the discharge voltage. A voltage generator 41 is connected via a line to a stationary sliding contact 42. The sliding contact 42 comes successively into electrical contact with the upper side of the respective, surrounding flat bars 13, which are guided past the sliding contact 42 in the working direction D. On the underside of the flat bar 13, the already mentioned clothing strip 20 is provided, in which the clothing 21 is inserted in the form of clothing needles. The clothing needles penetrate the clothing strip 20, wherein the ends of the needles facing away from the clothing tips rest on the underside of the flat rod 13 with electrical contact formation. The flat bar 13 is electrically insulated from the two flexible sheets 12; the flexible bows are for this purpose made for example of plastic.

The voltage generator 41 is further connected via a line with a stationary sliding contact 43, which rests against the drive shaft 5 a of the only partially illustrated drum 5. About the drum shaft 5a and the walls of the drum 5, the generator 41 is electrically connected to the drum set 25. By applying a variable voltage, a spark discharge can be generated from the tips 22 of the flat clothing 21 to the tips 26 of the drum assembly 25, which bridges the carding gap 6 between the tips 22, 26 and causes a short circuit in the circuit. The discharge voltage is measured by a parallel to the transformer 41 connected voltmeter 49 and transmitted to an evaluation unit 50. The evaluation unit 50 calculates, by means of a stored algorithm, the instantaneous distance δ (carding gap) between the clothing tips 22, 26 which exists during the voltage or spark discharge. Via a display 52, this distance can be displayed, for example. If the carding gap δ is too small, which causes a fear of a collision of the tips 22, 26, an optical and / or acoustic warning signal can be output via a signal device 53. Alternatively and / or additionally, the traveling lid arrangement 6 and / or the drum 5 stopped. Likewise, it may be provided that the evaluation unit 50, which may be designed as a microcomputer, outputs a control command to an actuator 51, which re-sets the flexible bend, which in turn affects the distance δ of the tips 22, 26 (see also FIG FIG. 3 ).

Advantageously, the carding nip δ can be viewed from the side of the machine, so that an operator can also optically control the generation of spark and possibly use it for manually setting the carding gap δ by means of the flexible bends 12.

In the FIG. 5 a simple measuring arrangement for generating the sparks and measuring the discharge voltage is shown. A high voltage source 101 charges a capacitor 103 via a variable resistor 102, the magnitude of the set resistance determining the discharge frequency and the capacitance of the capacitor 103 determining the discharge energy. The high voltage source 101 is connected to the clothing 21 via a stationary sliding contact 42. A stationary sliding contact 43, which rests against the drive shaft 29 of the only partially illustrated drum 5, is grounded. During a voltage discharge between the two sets 21, 25, the capacitor 103 discharges, wherein the discharge voltage is measured by a voltage measuring arrangement 104, which has a high-impedance input.

In the FIG. 6 is the time course of the voltage applied to the tips 22 voltage shown (more precisely, the potential difference between the tips 22, 26), in which case a repetition sequence is selected from a plurality of successive rising and falling edges in the form of a sawtooth. This increases linearly from zero to the voltage U _max , and then abruptly drops to zero. In this area A, in which no spark discharges occur, the actual distance δ _A (measuring distance) of the clothing tips 22, 26 is greater than the maximum measurable carding gap δ _MAX .

In the area B, however, the measuring distance δ _{B is} between 0 and δ _MAX , so that spark discharges occur at a breakdown voltage of U _E , ie the potential difference between the clothing tips 22, 26 is so great that a Spark discharge occurs, a short circuit occurs and therefore the voltage drops quickly to zero, then to rise again linearly according to the predetermined voltage curve. The frequency of the sawtooth voltage is set so that it always - even at large instantaneous relative speeds between flat set 21 and drum set 25 - detects all possible peak and thus discharge positions. In this case, the discharge voltage U _E for subsequent electrical discharges (spark discharges) is substantially the same, provided that the distances to be measured are also identical.

In the region C, the measuring distance δ _{C is} smaller than δ _B , so that the breakdown voltage U _E , is smaller than the breakdown voltage U _E in the region B. Therefore, the frequency of breakdowns or the occurrence of spark discharges in the region C is greater than in Area B.

In the lower half of the FIG. 6 the discharge currents are shown shortly after the spark discharges as a function of time. These short-circuit currents only flow for a short time, since the voltage U has also dropped to zero. The maximum flowing current is designated here by I _E. If necessary, it is also possible to draw conclusions about the set spacing δ from the magnitude of the current value.

Finally, in the area D, the situation of a short circuit is shown in which a constant short-circuit current flows.

Both in the region B and in the region C, it is also shown in each case how fibers, in particular, can influence the discharge voltage or the discharge current (see in each case marked with an asterisk). The breakdown voltage caused by fibers is smaller than with fiber-free carding nip δ. Accordingly, the discharge current is smaller (see lower half of FIG. 6 ). In addition, for example, statistical calculations can be carried out by means of several measurements, with the aid of which a separation of the measured values in the case of discharges in the presence of fibers from those in fiber-free air can be carried out. In this way, an exact determination of the carding gap δ in fiber-free air is possible.

In the FIG. 7 a measuring arrangement is shown, with which a measurable plasma current is generated. For this purpose, a voltage source 201 for generating a low voltage to a voltage regulator 202 is connected to the controllable input of the output of a switching unit 203 is connected. The output of the voltage regulator 202 is connected to the input of a first Kommutationsblocks 204, whose other input is fed by a pulse shaper 207. A second commutation block 205 also receives corresponding signals from the pulse shaper 207. The second commutation block 205 is further connected to a signal shaper 206, which outputs a sawtooth-shaped voltage. The respective output of the two commutation blocks 204, 205 is connected to a measuring resistor 208, which is connected between two inputs of the mentioned switching unit 203. In addition, a measuring channel 209 is connected to one of these two inputs, with which the height of the low or low voltage for the maintenance of the plasma flow is measured. A third input of the switching unit 203 is the voltage tap of an adjustable resistor 210, with which the desired plasma current is adjusted.

The operation of the circuit arrangement according to the FIG. 7 is as follows: The two Kommutationsblöcke 204, 205 are controlled by the pulse shaper 207 alternately. If the commutation block 205 in the in FIG. 7 illustrated position is the sawtooth voltage from the signal shaper 206 between the sets of flat bar 13 and drum 5 at. If breakdown occurs, the voltage breaks, which is registered by the switching unit 203. This gives a signal to the pulse shaper 207, which now switches the two Kommutationsblöcke 204, 205 in the other switching state. Now the voltage from the voltage regulator 202 is applied to the measuring resistor 208 and is registered by the measuring channel 209. The magnitude of this voltage (the voltage for maintaining the plasma current across the clothing gap .delta.) Is determined by the switching unit 203, which processes the setpoint plasma current set at the resistor 210 for this purpose.

In the FIG. 8 a voltage-time diagram and a current-time diagram for the case of plasma generation for Kardierspaltbestimmung is reproduced. As with the FIG. 6 In this case, a sawtooth-shaped voltage U is applied. The areas A and D correspond to those in the FIG. 6 , On the other hand, at a voltage U _{E, B} (for the region B) or U _{E, C} (for the region C), which are each below the maximum voltage U _max , spark discharges are generated with the discharge current I _{E, B} or I _{E , V} caused. However, the voltage is then adjusted in such a way to a voltage value U _{P, B} or U _{P, C} , that in each case a substantially constant plasma current I _P flows. Below this erasing voltage U _{P, B} or U _{P, C} , the plasma would collapse and no plasma current I _{P would} flow. The two parameters U _P , I _P are known, functionally related to the distance δ of the clothing tips 22, 26, so that also in this way, the width of the carding gap δ can be measured directly and without contact.

Like in the FIG. 6 are shown at the marked with a star points of fibers produced punctures.

In the FIGS. 9 and 10 an embodiment is shown, by means of which reference measurements can be made. A reference electrode pair 71, 75 is mounted within a fiber guiding element 60, which thus has a double function. The fiber guiding element 60 is located between the traveling lid arrangement 6 and a carding element 10 (both not shown here, but see FIG FIG. 1 ). On the underside of the Faserleitelements 60, the outer surface of the drum 5 opposite, a narrowing drum in the direction of rotation gap 61 is provided to compress the entrained by the drum 5 air L (dashed dotted line). This is followed in the flow direction of the air L an opening 62, through which the air L penetrates into the interior of the Faserleitelements 60. The concave shape and the size of this opening 62 prevent fibers from entering the interior of the fiber guiding element 60. The substantially fiber-free air in the housing of the fiber guiding element 60 continues to circulate through a downstream opening 63 on the underside of the fiber guiding element 60, wherein an additional dynamic negative pressure, which arises in the widening, subsequent column 64, supports the air flow movement. The openings 62 and 63 can successively in a line or offset (see the supervision according to the FIG. 10 ) can be arranged.

In the interior of the fiber guiding member 60, a closed space is defined by walls 65 and the removable cover 66 (shown in FIG. 9, in FIG FIG. 10 decreased). In this space there is the reference electrode pair, on the one hand a fixed electrode 71 which is arranged on an insulator 72 and an electrode tip 73 made of a platinum alloy, and on the other hand by hand at a distance from the electrode 71 adjustable electrode 75 with an electrode tip 76th also comprising a platinum alloy. The electrode 75 is pivotally attached to a leg 79. The said distance is set by a leg 79 passing through the adjusting screw 77, which acts on the acted upon by a spring 78, pivotable electrode 75. The electrode 75 is z. Example, electrically to the ground and the electrode 71 by means of a guided through an insulator 67 in the cover 66 cable 68 to a measuring unit or a voltmeter 49 (s. FIG. 4 ) connected.

The electrode tips 73 and 76 have the main geometry features of the tips 26 of the drum set 25 (radius R ₁ , angle α ₁ ) and the tips 22 of the flat clothing 21 (radius R ₂ , angle α _2. ). These geometric properties have a direct effect on the corona effect and thus allow comparable results between the reference discharges between the electrodes 71, 75 on the one hand and the Meßentladungen between the tips of the flat clothing 21 and the drum set 25 on the other. By setting the distance between the electrodes 71 and 75 to a value δ _v (= δ _comparison ), which is similar to the expected clothing spacing δ, the conditions are created, influences the surface geometries of the sets 21, 25 and the micro-operation climate factors to eliminate the measuring discharges. For this purpose, the known distance between the reference electrodes 71, 75 and the comparable surface geometry of the reference electrodes 71, 75 is used. The term "micro-operating climate" is to be understood in particular as the air temperature, the air humidity, the air velocity, the presence of ionizing particles and / or residual ionizations. Under Design geometries are to be understood in particular the values of the point angles of the sets 21, 25 and the values of the tip radii.

In the FIG. 11 is an example of an electromechanical solution for adjusting the distance of the reference electrode pair 71, 75 reproduced. With otherwise identical components (with the same reference numerals) as in the embodiment according to the FIGS. 9 and 10 an electric motor 177 acts on the electrode 75. Thus, the distance δ _{V can} also be adjusted during the carding operation to a new set desired spacing by the motor 177 is driven by a controller, not shown.

In the FIG. 12 the distance between the reference electrodes 71, 75 is adjusted by means of piezoelectric components. On the electrically non-conductive support plate 80, two piezoelectric, equal sized actuators 81 and 82 are arranged. At these two electrodes 71 and 75 are connected, which in the present case are both designed to be movable. By this arrangement, the thermal expansion of the two actuators 81, 82 is compensated. If the two piezo actuators 81, 82 are subjected to the same control voltage in a parallel circuit with a reverse polarity, the distance δ _{V of} the two electrodes 71, 75 from each other during production to a new set desired spacing can be adjusted.

In the FIG. 13 Another embodiment of the invention is shown to measure the discharge voltage U _E. Here, not the flat bar 13 serves as a conductor, but between flat bar 13 and clothing strip 20 arranged surface element 30 which is at least partially formed electrically conductive on its underside, but has no electrical contact with the flat bar 13 at the top. In the FIG. 13 are flat bar 13, surface element 30 and clothing strips 20 shown in exploded view. When used in the machine these elements abut each other and are by means of brackets 16 (see FIG. 2 ) held together.

In the FIG. 14 a portion of a clothing strip 20 is shown from the side through which the clothing needles of the clothing 21 are pushed from above. The clothing strip 20 is usually made of a textile or leather material. The rear legs 23 of the clothing needles 21 bear against electrically conductive sections, the conductive zones 34 designated here as such, so that current can flow from the tips 22 of the clothing 21 to the conductive zones 34: the conductive zones 34 are embedded in the planar element 30, imprinted, glued or otherwise provided on the surface element 30.

In the FIGS. 15 and 16 show two different embodiments of surface elements 30 and 30 'from the bottom. The embodiment of the FIG. 15 has three guide zones 31, 34, 37, which are arranged electrically isolated from one another in the longitudinal direction of the surface element 30. These guide zones 31, 34, 37 are connected via signal lines 32, 35, 38 with contacts 33, 36, 39 at the end faces of the surface element 30, which correspond to stationary, opposite sliding contacts. Each of these contacts 33, 36, 39 is connected to the voltmeter 49 (s. FIG. 4 ) to spatially resolved to detect the voltage discharges in the region of the respective guide zones 31, 34 and 37, respectively. This makes it possible, for example, to make statements about the state of the tips in the carding zones assigned to the various guiding zones.

The embodiment according to the FIG. 16 also offers the possibility of a spatially resolved measurement across the width of the surface element 30 and thus the clothing strip 20. Here, six guide zones are provided, with two guide zones 31 'and 34' and 37 'in the direction of movement of the flat bar 13 next to each other. These paired guide zones 31 ', 34' and 37 'are - as in the embodiment according to the FIG. 15 - Distributed over the length of the surface element 30 '. This arrangement makes it possible to measure the voltage discharges in six different areas in a spatially resolved manner. The arrangement of the lines 32 ', 35', 38 'and the contacts 33', 36 ', 39' at the end faces of the surface element 30 'correspond to those of FIG. 15 , By the Arrangement according to FIG. 16 if necessary, an assessment of the state of the flexible sheet 12 (s. FIGS. 1 . 3 . 19 ) possible.

In addition to the registration of the distance between the clothing tips 22, 26 on the basis of the discharge or erase voltage, it is also possible to use the frequency and / or the number and / or the type of discharges for the evaluation; the necessary counting or measuring devices are not shown in detail. For example, based on a statistical evaluation of the signals can be closed to the conditions in the carding, for example, on the fiber assignment. If necessary, this information can also be used to more accurately determine the clothing tip spacing δ and / or the wear state of the clothings in different carding areas.

In the FIG. 17 an embodiment of the invention is shown to realize individual distance measurements between individual flat clothings 21 and the drum set 25. For this purpose are according to FIG. 17 provided three stationary measuring points for measuring the discharge voltages, via the flexible sheet 12 (s. FIG. 1 ) are distributed and at each of which a sliding contact 44, 45, 46 with the respective just transported over the flat bar 13. Each sliding contact detects only one flat bar 13. Each successive flat bars 13 are in the region of the sliding contact 44 with i-1, i, i + 1, in the region of the sliding contact 45 with j-1, j, j + 1 and in the region of Sliding contacts 46 with k-1, k, k + 1 called. The sliding contacts 44, 45, 46 of the three measuring points are connected via connecting lines to independent measuring channels, which are designated here by Roman numerals I, II and III and part of a measuring and evaluation unit 50. Alternatively, only one measuring channel is present, which commutatively processes the signals from the sliding contacts 44, 45, 46. The sliding contacts 44, 45, 46 are - as based on the FIGS. 4 . 5 . 7 already explained - connected to voltage sources not shown here.

The execution according to the FIG. 17 also has two further measuring points 47, 48. On the one hand, this is a non-contact detection (eg, inductive, optical, ultrasound, etc.) on the top of the revolving lid assembly 6 (measuring point 47), with a with "1" marked flat bar 13 is detected from the total number n of the flat bars by means of a sensor 91, which allows an assignment of the measured distances to the respective flat bars i, j, k. The further measuring point 48 with a non-contact measuring sensor 92 is provided in the region of the axis of rotation of the drum 5 and reports the instantaneous angular position of the drum 5 on the basis of a cam 5a placed on the axis 5b to the geometric inaccuracies of the drum outer surface (such as roundness error) from the using the measuring channels I, II and III to calculate distance measurements.

At each of the three sliding contacts 44, 45, 46, the distance δ of the respective flat clothing 21 of each flat bar 13 from the drum set 25 can be determined with the aid of the voltage measured values (see FIG. FIG. 6 or FIG. 8 ) be determined. In the FIG. 18 these detected values are shown in more detail, wherein on the y-axis for each flat bar k, k + 1, k + 2, ..., j, j + 1, j + 2, ..., i, i + 1, i + 2, ... the measured carding gap δ is plotted as a function of time for the three measurement channels I, II and III.

With the help of the embodiment of FIG. 17 and based on the in FIG. 18 As shown, the degree of wear of each individual flat garniture 21 or any damage thereto can also be determined. Also, in this way the tightening angle or inclination angle of the flat clothing 21 relative to the drum 5 (s. FIG. 2 ) are measured.

In the FIG. 19 a further embodiment is shown, in which case over almost the entire carding area, ie here over a measuring range with an angle β, the course of the carding gap δ is measured by means of the measurements of the discharge voltages. At least one long sliding contact 144 stretches over this measuring range β, which comes into electrical contact along the upper side of a specially prepared reference flat bar 13 along the latter. Thus, the carding gap 6 can be measured over the entire path of this flat bar 13.

Preferably, a spatial resolution of the Kardierspaltmessung across the width of this flat bar 13, that is provided transversely to its direction of rotation. This is For example, on the left and the right side of the flat bar 13 and in its center a respective sliding contact provided, for this purpose, for example, a surface element 30 with three distributed over the width of guide zones 31, 34, 37 corresponding to FIG. 15 can be provided. The contacting of these conductive zones can be realized for example via three adjacent sliding contacts, wherein in the FIG. 19 only such a sliding contact 144 is shown; are accordingly in the FIG. 19 However, three connecting lines are shown leading to a "measuring channel left", a "measuring channel center" or a "measuring channel right". Again, a commutating measuring channel can alternatively be provided.

The measuring points 47 and 48 with their sensors 91 and 92 correspond to those of FIG. 17 ,

In the FIG. 20 By way of example, the size of the carding gap 6 is plotted over the measuring range β for the three measuring channels. These hypothetical curves would give a user of the card hints in which areas of the measuring range β of the carding nip δ should be readjusted, in particular by replacing flat bars 13 and / or by readjustment of the flexible sheet 12 (s. FIGS. 1 and 3 ).

Analogous to the embodiment according to the FIG. 17 is also at the in FIG. 19 shown embodiment, a non-contact measurement of the position of a particular flat bar (marked "1") is provided. Similarly, non-circularities of the drum 5 are detected by means of a non-contact measurement on the drum shaft 5a.

The present invention is not limited to the illustrated and described embodiments. Thus, with reference to the figures, the distance measurement between the clothing tips 22, 26 of flat clothing 21 and sawtooth assembly 25 of a carding drum 5 has been described. Without limitation, the described measuring principle is also for distance measurement between the Sägezahngarnituren the drum 5 and a breeze (see FIG. 1 ) transferable. Likewise, others are Possibilities for electrical contact formation possible, for example drum side by tapping on an annular flange of the drum 5 instead of the drum shaft. Also, for the voltage tap in the region of the flat bar 13, a stationary busbar can be arranged at least on one end face, which is in sliding contact with the flat bar (in the embodiment according to FIGS FIG. 4 ) or with the contacts 33, 36, 39 and 33 ', 36' and 39 '(in the embodiments according to the FIGS. 15, 16 ) come. Instead of sliding contacts other voltage taps can also be used.

If the term "spark discharge" was used in the preceding, it also includes voltage discharges that are barely or not visible to the naked eye.

The invention therefore relates to a spinning preparation machine, e.g. Carding, carding, cleaning or the like., With a device for non-contact measuring and / or setting of parameters at two opposite sets (21, 25). The tips (22, 26) of the trimmings are in this case made electrically conductive, a voltage source (41, 101, 201, 206) is connected to tips of at least one of the trimmings, and electrical voltages can be generated by applying a variable potential difference between the tips of the two trimmings , These give an indication of the current distance (δ) and / or the distance to be set between the clothing tips and / or the degree of wear of at least one of the trimmings and / or the positioning of one clothing to the other clothing, in particular their inclination angle (Θ) to each other. Likewise, the invention relates to a corresponding non-contact measuring method.

Claims (37)

1. A spinning preparation machine, e.g. a carding machine, a cleaner or the like, comprising a device for contactless measurement and/or adjustment of parameters in two opposite card clothings (21, 25), characterised in that the tips (22, 26) of the clothings (21, 25) are electrically conducting, a voltage source (41; 101; 201, 206) is connected to tips (22, 26) of at least one of the card clothings (21, 25) and electric discharges can be produced by applying a variable potential difference between tips (22, 26) of the two card clothings (21, 25), which give an indication of the actual distance (δ) and/or the distance to be adjusted between the card clothing tips (22, 26) and/or the degree of wear of at least one of the card clothings (21, 25) and/or the positioning of one card clothing (21) with respect to the other card clothing (25), in particular their angle of inclination (Θ) relative to one another.
2. The machine according to any one of the preceding claims, characterised in that there is provided an evaluation unit (50) which can determine the distance (δ) between the card clothing tips (22, 26) from the registered frequency and/or number and/or type of discharges and/or at least one electrical parameter in relation to the at least one electric discharge.
3. The machine according to any one of the preceding claims, characterised in that the voltage value (U_E) before the electric discharge (spark discharge) can be recorded by a voltage measuring device (49; 104; 209), wherein this voltage value corresponds to a value for the shortest distance (δ) between the card clothing tips during the spark discharge.
4. The machine according to any one of the preceding claims, characterised in that the voltage source (41; 101 + 102 + 103; 206) is configured as a voltage generator (pulse generator) for generating a variable voltage, for example, a sawtooth voltage or a DC voltage having sawtooth peaks.
5. The machine according to any one of the preceding claims, characterised in that an additional electrode pair (71, 75) for the electric discharge is provided as a reference measuring unit, whose optionally variable distance is known and which has a similar surface geometry to said card clothing tips (22, 26) at the tips (73, 76).
6. The machine according to any one of the preceding claims, characterised in that the additional electrode pair (71, 75) is located outside the carding region of the spinning preparation machine configured as a carding machine.
7. The machine according to any one of the preceding claims, characterised in that the additional electrode pair (71, 75) is located in a space into which substantially no fibres can penetrate during operating of the spinning preparation machine (1).
8. The machine according to any one of the preceding claims, characterised in that the additional electrode pair (71, 75) is located in a space through which an air flow (L) is passed during operation of the spinning preparation machine (1).
9. The machine according to any one of the preceding claims, characterised in that the two card clothings (21, 25) together with their intermediate space are visible for the operator in such a manner that the electric discharges can be monitored visually.
10. The machine according to any one of the preceding claims, characterised in that one card clothing (21) is the flat clothing of a carding machine (1) and the other card clothing (25) is the associated cylinder clothing.
11. The machine according to any one of the preceding claims, characterised in that the two card clothings (21, 25) revolve either in the same direction or in opposite directions.
12. The machine according to any one of the preceding claims, characterised in that the flat bars (13) are electrically insulated with respect to the two quadrants (12) on which the front sides of the flat bars (13) temporarily rest during a revolution.
13. The machine according to any one of the preceding claims, characterised in that potential differences between the card clothings (21, 25) can be generated over the entire carding width (B).
14. The machine according to any one of the preceding claims, characterised in that at least one sliding contact (42, 43; 44, 45, 46; 144) is provided for making contact on the flat bars (13) and/or the cylinder shaft (46), wherein at least one of the sliding contacts (42, 43; 44, 45, 46; 144) is connected to a voltage source (41).
15. The machine according to any one of the preceding claims, characterised in that a plurality of sliding contacts (43, 44, 45) not connected electrically to one another, are provided along the carding path for making contact with various flat bars (13).
16. The machine according to any one of the preceding claims, characterised in that at least one elongated sliding contact (144) is provided along at least one partial section of the carding path with which at least one carding bar (13) is in electrical contact during transport along the cylinder (5).
17. The machine according to any one of the preceding claims, characterised in that a plurality of elongated sliding contacts (144) are provided when viewed over the width of a flat bar (13), which contacts are in electrical contact with various electrically separate zones of the card clothing (21) of the at least one flat bar (13).
18. The machine according to any one of the preceding claims, characterised in that at least one surface element (30) which is electrically conducting at least in sections is provided between the flat bar (13) and card clothing strips (20), which element is in electrical contact with the card clothing ends (23) facing away from the card clothing tips (22) and via which the discharge current produced during the electric discharge flows.
19. The machine according to any one of the preceding claims, characterised in that at least one surface element (30) has a plurality of conducting zones (31, 32, 33; 31', 32', 33') which are electrically separated from one another, which are distributed over the length and/or over the width of the associated card clothing strip (20).
20. The machine according to any one of the preceding claims, characterised in that a maximum distance-related potential difference which exceeds the breakdown strength of air, can be set between said tips (22, 26) of the two card clothings (21, 25) depending on the desired measurement range in the range between 1000 and 10 000, preferably between 2000 and 5000 V, and preferably between 2500 and 3500 V.
21. The machine according to any one of the preceding claims, characterised in that the card clothings (21, 25) and the impedance of the voltage source are tuned to one another in such a manner that the discharge energy during the measurement is limited to below 10 mJ, preferably to below 5 mJ and preferably to below 1 mJ.
22. The machine according to any one of the preceding claims, characterised in that the card clothings (21, 25) are arranged with respect to one another and said potential difference can be applied by a voltage source (201) in such a manner that following a voltage discharge a plasma is formed for a short time interval between the card clothings (21, 25).
23. The machine according to any one of the preceding claims, characterised in that the voltage for maintaining a plasma current or the plasma extinguishing voltage (U_P) can be recorded.
24. The machine according to any one of the preceding claims, characterised in that the evaluation unit (50) for determining the distance (δ) of the card clothings (21, 25) or for evaluation the electric discharge is connected to adjusting means (51) for adjusting the distance (δ) between the two card clothings and can transmit a command for adjusting the distance to these.
25. The machine according to any one of the preceding claims, characterised in that if the distance (δ) between the clothing tips (22, 26) falls below a predetermined level, a collision warning can be delivered by means of a signal device (53) and/or a suitable measure can be taken to prevent a collision.
26. A contactless measuring method in the area of two opposing card clothings (21, 25) on a spinning preparation machine, in particular a carding machine (1), a cleaner or the like wherein the card clothing tips (22, 26) consist of an electrically conducting material, characterised in that a variable potential difference is generated between the tips (22, 26) of the two card clothings (21, 25) to produce an electric discharge between the tips (22, 26) wherein the distance (δ) between at least a part of the card clothing tips (22, 26) and/or the degree of wear of at least one of the card clothings (21, 25) and/or the positioning of one card clothing (21) with respect to the other card clothing (25), in particular their angle of inclination (Θ) relative to one another, is determined from the frequency and/or the number and/or the type of discharges and/or at least one electrical parameter in relation to the electric discharges.
27. The method according to any one of the preceding process claims, characterised in that there is provided an additional electrode pair (71, 75), whose optionally variable tip distance (δ_V) is known and which is located in the same operating microclimate as said card clothings (21, 25), wherein this additional electrode pair (71, 75) is used as a reference measuring unit in order to calculate the influences of the operating microclimate on the measured values of the electric discharge.
28. The method according to any one of the preceding process claims, characterised in that there is provided an additional electrode pair (71, 75) whose optionally variable tip distance (δ_V) is known and which has a similar surface geometry to said card clothings (21, 25) at the tips (73, 76), wherein this additional electrode pair (71, 75) is used as a reference measuring unit in order to take into account the influences of the surface geometry on the measured values of the electric discharges between the card clothings (21, 25).
29. The method according to any one of the preceding process claims, characterised in that a repetition sequence comprising a plurality of successive ascending and descending flanks is used as the voltage, wherein the frequency of this repetition sequence is matched to the rotational speed of one or both card clothings (21, 25).
30. The method according to any one of the preceding process claims, characterised in that a repetition sequence comprising a plurality of successive ascending and descending flanks is used as the voltage, wherein the frequency of this repetition sequence is matched to the number of card clothing tips (22, 26).
31. The method according to any one of the preceding process claims, characterised in that the voltage value (U_E) is measured directly before a voltage discharge.
32. The method according to any one of the preceding process claims, characterised in that following a voltage discharge a plasma is generated in the intermediate space between the two card clothings for a time interval in the millisecond range or below, wherein the distance between the card clothing tips (22, 26) is determined or adjusted from the plasma voltage for maintaining the plasma current or from the extinguishing voltage.
33. The method according to any one of the preceding process claims, characterised in that a separation is made by means of statistical calculations between measured values for discharges in the presence of fibres and measured values in a discharge in fibre-free air.
34. The method according to any one of the preceding process claims, characterised in that for the purpose of adjusting the distance between the card clothing tips (22, 26) over the entire width of the flat clothing (21), a first side of the flat clothing (21) is adjusted so that the measured voltage (U_E) directly before the electric discharge corresponds to a desired card clothing distance (δ) for this first side and then the second side is lowered or optionally raised again until the same voltage (U_E) and therefore the same card clothing distance (δ) as on the first side is present on this second side.
35. The method according to any one of the preceding process claims, characterised in that on the basis of the determined voltage (U_E) a collision warning is given if the distance (δ) between the card clothing tips (22, 26) falls below a predetermined value.
36. The method according to any one of the preceding process claims, characterised in that signals from electrical taps associated with a flat, which are electrically insulated from one another and associated with different carding zones of the flat are evaluated to assess the state of the tips in the various carding zones.
37. The method according to any one of the preceding process claims, characterised in that signals from electrical taps associated with a flat, which are electrically insulated from one another and associated with different carding zones of the flat located one after the other in the direction of revolution, are evaluated to assess the state of the flexible arc (12).

Images